This invention pertains to valves which control flow between outside and inside a tubular member. More specifically, this invention pertains to a valve of the concentric gas lift or chemical injection type, which may be included in a well tubing in a well produced by gas lift methods, to control flow of well annulus pressured lift gas into the tubing, or the valve may also be included in a well tubing to control flow of liquid chemicals from the well annulus "injected" into the tubing to inhibit tubing corrosion, dissolve paraffin, or the like. The control valve of this invention has the same general function in a gas lifted well as the gas lift valves shown in U.S. Pat. Nos. 2,642,889, 2,875,775, and 3,223,109 to Cummings and 2,954,043 to Canalizo. The aforementioned gas lift valves are annular type valves with valve seals of resilient material.
Resilient seals used in gas lift and injection valves are subjected to damaging erosive and abrasive flow. As flow volume through these valves over the seal increases, damage to resilient seals from erosion and abrasion and forces tending to wash the seal away are greater, and damaged seals cause leakage after valve closure. When flow control valves are closed and sealing, higher pressure differentials across the valves induce compressive stresses into the resilient valve seals which cause seal failures, leakage, and initiation of expensive repair procedures. Frequent and repeated stressing and flexure of resilient materials resulting from repeated valve openings and closings also contributes to early failure.
U.S. Pat. No. 4,134,454 to Donald F. Taylor, herein incorporated by reference, discloses a valve generally similar to the control valve of the present invention, in a well production system utilizing a centrifugal pump to produce the well, which is provided with variable and staged flow restrictors upstream and downstream of the valve to protect the resilient valve seal and greatly extend its operational life. None of the prior patents found show or teach the use of the valve of the Taylor patent in gas lift or chemical injection well systems.